Put Block doesn't work on another screen

Put Block works in his original screen (1), but not in another screen (0)

Example :

Screen Open 1,320,240,32,Lowres
Curs off : Flash Off
Ink 4
Circle 50,50,25
Wait Vbl
Get Block 1,0,0,100,100
' Draw Block 1 in his original screen 1 : OK
Put Block 1,100,100
Repeat : Until Mouse Key
Screen Open 0,320,240,32,Lowres
Curs off : Flash off
Cls 5
' Draw Block 1 in another screen 0 : Error Block not defined at line 14
Put Block 1,100,100
Wait Vbl
End